Electrical resistance



W. W. COBLENTZ.

ELECTRICAL RESISTANCE.

APPLICATION FILED sEPT.22. 1920.

Zlvwemtoz UNITED STATES WILLIAM W. COBLENTZ, OF WASHINGTON, DISTRICT OF COLUMBIA.

ELECTRICAL RESISTANCE.

Specification of Letters Patent. Patented June 6, 1922.

Application filed September 22, 1920. Serial No. 412,049.

,T all whom it may concern:

Be it. known that I, WILLIAM W. Co-

BLENTZ, a citizen of the United States of America, residing at Vashington, in the District of Columbia, have invented a cer tain new and useful Improvement in Electrical Resistan'ces, of which-the following is a specification.

This invention relates to improvements in electrical resistance, having for an object to provide a light reactive or photo-sensitive resistance which when interposed in an electrical circuit, may have its electrical conductivity either increased or decreased ac cording to the particular wave length or the color of light directed thereonto.

It is also an object of the invention to provide a resistor which upon the reversal of travel of current therethrough, will offer increased resistance to such current, which resistance, at times, has been found to be 50 per cent greater than that offered to the passage of the current in its initial direction through the resistor. v

I have found through process of experimentation that samples of molybdenite (sulphide of molybdenum) have the property of undergoing a change in electrical resistance when exposed to light. Furthermore I have also found that by applying a suitable voltage to the terminals of the cyrstal and exposing the photo-sensitive material to light of certain wave lengths. namely, less than 0.65 micromillimeters, the electrical resistance thereof will be increased above that which obtains in the dark, while for other wave lengths. namely, greater than 0.65 microfnillimeters, the resistance is decreased.

I am of course aware thatthe fact that a substance is photo-positive or photo-negative in its change in electrical conductivity is not new, my invention residing in the fact that this property is a function of theapplied voltage.

Ihave also ascertained that a resistor of lnolybdenite may be soldered directly to copper wires, etc., without previous electroplating, by means of VVoods alloy or ordinary solder, thus affording a positive. con nection with the terminals of the electrical circuit in which the resistor is arranged. It is, however, obvious that molybdenite can be utilized as a portion of an electric circuit and that its resistance to the passage of current through such circuit can be made to vary according to the intensity and the wave length of'the rays of thermal radiation directed onto the substance.

As a resistor, it has been found that-the actual dark resistance of a molybdenite body is approximately from ten thousand ohms to several million ohms, depending upon the length, width, and thickness of the material use 1 I Other objects will be in part obvious and in part pointed out hereinafter.

In order that the invention and its mode of application may be readily understood by workers skilled in the art, I have in the accompanyingillustrative drawings and in the detailed following description based thereon, set out one practical embodiment of the same.

In the.drawings; I

Figure 1 is a diagrammatic view of the light reactive resistance arranged in an electrical circuit and adapted to have its resisting qualities varied by light rays projected thereonto; and.

Figure 2 is a detail partly in section showing the connection of the molybdenite resistor with suitable electrical terminals.

Having more particular reference to the drawings, in connection with which like characters of reference will designate corresponding parts throughout the several views, and referring in particular to Figure 1, it will be here seen that the light reactive resistance element 1 is interposed in the conductors .2 forming an electrical circuit and including therein a source of ener 3.' A reversing switch 4 may be and pref i ei 'ably is interposed in-this circuitvas clearly shown, while contact terminals 5 are arranged in one side of the circuit and are adapted to have certain electrically operated or responsive devices connected thereto, in order that the qualities of the same may be controlled with the increase and decrease in resistance of said light reactive resisting body 1.

A source of light 6 is positioned at a point spaced from the resistor 1 and is adapted to have the rays therefrom projected through a lens 'Z which in turn has interchangeably positioned before the same a transparenttcolor screen 8, which, by way of illustration, may be an ordinary ruby'glass. A second color screen not shown is also provided and is adapted to be substituted for the lens 7 the color of this particular screen being such as to absorb all rays having wave lengths greater than 0.65 micromillimeters while the ruby screen will absorb all rays of Wave lengths less than 0.65 micromillimeters. 'ith the projection of the ruby rays onto the light reactive resistance 1, the conductivity thereof will be increased and in consequence, the resisting qualities of this body will be decreased. However, when rays of wave lengths less than 0.65 micromillimeters. that is. of either violet, blue, green, greenish yellow. or yellow, colors, are directed onto the resistance 1. its resisting qualities will be increased and therefore, the electrical contact of the same will be materially decreased. Hence, with the connection of various electrically operated or responsive apparatus or devices to the contact terminals 5, the supply of current thereto will be regulated according to the electrical conducting qualities of the light reactive resisting body 1.

Furthermore. it has been found through actual experiment. that with the interpositioning of a light reactive resistance of molybdenite, sulphide of molybdenum, the passage of current in one direction therethrough will be permitted with but little resistance. but when the direction of travel of such current is reversed through the molybdenite resistor, the resistance to such flow is increased, at times, and depending upon the qualities of the molybdenite fifty per cent. Because of this. it is to be understood that the invention involves two phases, namely, the provision of a light reactive resistance in which electrical conductivity thereof will be varied with the projection of light rays of wave lengths greater and less than 0.65 mi cromillimeters thereonto, and secondly. the

provision of an electrical resistance which will have its resisting qualities increased upon the reversal of the direction of travel of current therefhrough.

The light reactive resisting body 1 may be secured to contact terminals 9 of the electric circuit by merely soldering the same thereto. either with Woods alloy or with ordinary solder. Hence, a positive and dependable connection between the resisting body and the conductors of said electric circuit will be insured.

Various other arrangements of the resistance herein described may be resorted to, such as conditions or preference may dictate. and therefore. such variations or modifications as are within the scope of my claims, I consider within the spirit of my invention.

I claim:

1. An electrical resistance composed of molybdenite.

2. Anelectrical light reactive resistance composed of molybdenite.

3. An electrical resistance consisting of a body of molybdenite variable in resistance by the action of radiant energy thereon.

4. An electrical resistance consisting of a body of molybdenite variable in its resistance by the intensity and wave length of rays of thermal radiation.

5. An electrical resistance consisting of a photosensitive body of molybdenite capable of having its conductivity varied by the intensity and wave length of rays of thermal radiation directed thereonto.

' 6. An electrical resistance comprising a body of molybdenite adapted to have its resistance increased upon the direction of rays of thermal radiation greater than 0.65 micromillimeters thereonto and such resistance decreased upon the direction of thermal rays of wave lengths less than 0.65 micromillimeters.

WILLIAM W. COBLENTZ. 

